Log Message:
www/hiawatha: Cmake changes

Switch from USE_CMAKE (mk/configure/cmake.mk) to including
devel/cmake/build.mk.

Stumbling stones were a custom CMAKE_BUILD_DIR for the sake of config
file generation (the paths could probably be patched), and the
CMAKE_ARGS -> CMAKE_CONFIGURE_ARGS conversion in options.mk, to make
sure we keep statically linking to mbedtls, instead of installing
private shared libs.